This invention relates generally to a key activated switch and, more particularly, to a key activated switch providing binary coded switching outputs for use with microprocessor-based equipment.
Key controlled switches have been proposed for providing access to microprocessor-based equipment. The functions of such switches are to prevent use of equipment by unauthorized personnel and to identify authorized users thereof. Typically key operated switches include a bank of micro-switches integrally mounted with a conventional cylinder lock. A front portion of a proper key enters and is bitted to operate the cylinder lock while an extended rear key portion is bitted to selectively engage and activate predetermined switches in the bank thereby providing a binary output. Examples of key controlled switches are disclosed in U.S. Pat. Nos. 4,198,552; 4,104,490; 3,912,888; and 3,427,413. Problems associated with prior key controlled switches have included inadequate reliability of operation, excessive component cost and labor intensive assembly requirements. These problems stem primarily from the tight tolerances required to reliably activate micro-switches with conventionally bitted keys.
The object of this invention, therefore, is to provide an improved and relatively inexpensive key controlled switch that can be reliably operated to provide a predetermined binary output.